Harpin and hydrogen peroxide both initiate programmed cell death but have differential effects on defence gene expression in Arabidopsis suspension cultures.
Programmed cell death is increasingly viewed as a key component of the hypersensitive disease resistance response of plants. The generation of reactive oxygen species (ROS) such as H2O2 triggers a cell death programme in Arabidopsis suspension cultures following challenge with the bacterial elicitor harpin. Both harpin and exogenous H2O2 initiate a cell death pathway that requires gene expression, and also act as signalling molecules to induce the expression of plant defence genes encoding enzymes such as phenylalanine ammonia-lyase (PAL), glutathione S-transferase (GST) and anthranilate synthase (ASA1), an enzyme of phytoalexin biosynthesis in Arabidopsis. H2O2 induces the expression of PAL1 and GST but not that of ASA1. Harpin initiates two signalling pathways, one leading to increased ROS generation and expression of PAL1 and GST mRNA, and another leading to increased GST and ASA1 expression, independent of H2O2.
Desikan
R
R
Department of Biological and Biomedical Sciences, University of the West of England, Bristol, Coldharbour Lane, Frenchay, Bristol BS16 1QY, U.K.
Reynolds
A
A
Hancock
J T
JT
Neill
S J
SJ
D000878:Anthranilate Synthase / Q000235:genetics*; D017209:Apoptosis / Q000187:drug effects*; D017360:Arabidopsis / Q000235:genetics*; D001425:Bacterial Outer Membrane Proteins / Q000494:pharmacology*; D002478:Cells, Cultured; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D005982:Glutathione Transferase / Q000235:genetics*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D016328:NF-kappa B / Q000502:physiology; D010650:Phenylalanine Ammonia-Lyase / Q000235:genetics*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D016328:NF-kappa B; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C075462:harpin protein, Erwinia amylovora; C087295:HrpZ protein, Pseudomonas syringae; D006861:Hydrogen Peroxide; D005982:Glutathione Transferase; D000878:Anthranilate Synthase; D010650:Phenylalanine Ammonia-Lyase